The structure 10 of an aircraft in particular comprises the hull structure and the floor structure. FIG. 1 illustrates an example of a connection according to the prior art between a hull structure 11 and a floor structure 12.
An orthonormal coordinate system (Oxyz) is defined.
The axis Ox corresponds to the longitudinal axis Ox of the aircraft. The front and the rear of the aircraft are defined along this axis Ox. The front of the aircraft corresponds to the nose side of the aircraft, where the cockpit is located. The rear of the aircraft corresponds to the tail side of the aircraft, where the vertical stabilizer is generally found. Hereinafter it will be considered that under normal flight conditions the aircraft moves along the axis Ox, along a vector oriented from the rear to the front of the aircraft.
The axis Oz corresponds to the vertical axis when the aircraft is located on the ground, in a parking position.
The axis Oy, with the axis Ox, defines a horizontal plane when the aircraft is located on the ground, in a parking position. The axis Oy corresponds to the transverse axis of the aircraft.
The hull structure 11 in particular comprises a set of frames 11A, forming stiffeners which are transverse relative to the axis Ox, and a set of stringers 11B, forming longitudinal stiffeners parallel to the axis Ox. The hull structure also comprises one or more metal or composite sheets shaped in accordance with the desired profile and referred to as the skin 11C. The skin 11C covers the lattice structure formed by the frames 11A and the stringers 11B.
The floor structure 12 comprises an assembly of crosspieces 12A and rails 12B. The rails 12B extend along the axis Ox and serve to fix furniture elements, such as the seats. The rail 12C is an external rail, i.e. a rail close to the hull structure or in other words close to the lateral walls of the aircraft. The crosspieces 12A extend along the axis Oy.
In the example shown in FIG. 1 the floor structure 12 is pressed against the hull structure 11 via the intermediary of stanchions 13 extending along the axis Oz.
In order to stabilize the floor structure 12, anti-crash connecting rods 14 extend in the plane (xOy). Each anti-crash connecting rod is an elongated rigid component, mounted fixedly at each one of its ends, on the floor structure on the one hand and on the hull structure on the other hand. In the example shown in FIG. 1 each anti-crash connecting rod 14 is fixed at a first point 14A to the external rail 12C and at a second point 14B to a stringer 11B. The first point 14A is located close to the intersection between the external rail 12C and a crosspiece 12A. The second point 14B is located close to the intersection between a stringer 11B and a frame 11A. Each anti-crash connecting rod 14 is inclined relative to the axis Ox.
The anti-crash connecting rods 14 make it possible to hold the floor structure 12 substantially fixed relative to the hull structure 11, even in the event of sharp deceleration of the aircraft, and in particular in the event of the aircraft crashing. A crash can be either a crash proper or an abrupt landing of the aircraft, or an impact approximating an abrupt landing in terms of the forces. In such a situation, the inertial force of the floor structure tends to move it away from the hull structure. In particular, the anti-crash connecting rods must be able to withstand an acceleration equal to 9 g along the axis Ox, towards the front of the aircraft (where g is the gravity of earth, equal to approximately 9.8 m·s−2). An acceleration towards the front of the aircraft (forward acceleration) may also be called “deceleration”. The force which acts on the anti-crash connecting rods is proportional to this deceleration and to the mass of the floor structure and the loads supported by the latter (aircraft furniture, passengers, etc.). In order to withstand such a deceleration, the anti-crash connecting rods have very wide sections and therefore a very considerable mass.